Spermatogenic cell apoptosis induced by mitomycin C in the mouse testis

Gonadal Degeneration Is Mediated by Apoptotic Processes in the Semelparous Gray Side-Gilled Sea Slug Pleurobranchaea maculata

AbstractSpecies undergoing postreproductive death experience great changes in their reproductive organs, which are driven by numerous physiological processes. To assess whether apoptotic processes are involved in the dynamics of the reproductive organs of Pleurobranchaea maculata, the gonadal structure of this semelparous side-gilled sea slug was studied using light and scanning electron microscopy. Apoptotic cells at different gonadal developmental stages were detected by in situ TUNEL assay. Apoptosis was primarily focused on spermatogonia during gonadal cell proliferation, probably as a regulatory mechanism that maintains homeostasis in reproductive cells. Visible gonadal degeneration at the end of the reproductive period is accompanied by apoptosis of the basal lamina cells of the acini, suggesting that apoptotic processes are involved in the gonadal degeneration observed in P. maculata.

Indian propolis ameliorates the mitomycin C-induced testicular toxicity by reducing DNA damage and elevating the antioxidant activity

Development of excellent curative therapy for most of the malignancies has resulted in a growing population of cancer survivors who are at increased risk for a variety of health problems including infertility. Therefore, fertility preservation has become an important issue during cancer treatment in recent years. Combination therapy with natural agents such as vitamins, antioxidants, dietary supplements, and plant products are considered as an attractive option to mitigate normal tissue toxicity imparted by chemotherapy. The aim of the present study was to explore the beneficial effect of hydroethanolic extract of Indian propolis (HEIP) on mitigating mitomycin C (MMC)-induced testicular damage and its mechanism of action. Healthy adult male mice were injected intraperitoneally with saline, MMC, HEIP and HEIP followed by MMC after 1h. The animals were dissected at 35days after various treatments to analyze testicular function. MMC administration resulted in significant reduction in testicular function in a dose-dependent manner at 35days after treatment which significantly improved by HEIP pre-treatment. At 24h after treatment, MMC induced significant increase in oxidative stress, γ-H2AX foci and expression of RAD51 and KU80 in testicular cells. Prior treatment with HEIP decreased the oxidative stress, reduced DNA damage and restored the testicular testosterone and inhibin B level. In conclusion, co-administration of Indian propolis extract may play a promising beneficial role in fertility preservation of males undergoing chemotherapy.

Interaction of exposure concentration and duration in determining the apoptosis of testis in rats after cigarette smoke inhalation

The effects of differences in smoke concentration and exposure duration in Sprague Dawley rats to determine variation in type and severity of the testis apoptosis were evaluated. The daily dosages were 10, 20 and 30 non-filter cigarettes for a period of 2, 4, 6, 8 and 12 weeks. Mainstream smoke exposure suppressed body weight gain in all regimens. A dose-related increase in plasma nicotine concentration was observed in smoke-exposed groups for 4, 6, 8 and 12 week regimens. Histopathological examination of the exposed groups showed disturbances in the stages of spermatogenesis, tubules atrophying and these appeared to be dose-related. Cytoplasmic caspase-3 immunostaining was detected both in Sertoli cells and germ cells in smoke-exposure groups. An increase in TUNEL-positive cells of testicular cells was observed after 6 weeks of cigarette exposure. The results indicate that cigarette exposure concentration and duration have interaction effect to induce apoptosis in the rat testes.

Histomorphometric effects of gemcitabine on Swiss albino mice spermatogenesis

BACKGROUND

Spermatogenesis is a highly conserved and regulated process and it is sensitive to fluctuations in the physical and chemical environment. Gemcitabine is a novel antimetabolic anticancer drug used frequently in the treatment of many cancers. This study aimed to investigate the histomorphometric effects of gemcitabine on spermatogenesis in Swiss albino mice.

MATERIALS AND METHODS

Gemcitabine in high and low doses (80 and 40 mg/kg) injected intraperitoneally to inbred Swiss albino mice. Gross testicular features and seminiferous tubular histomorphometry was studies at the end of 7(th), 14(th) day and at 2 months sperm shape abnormalities were studied.

RESULTS

Seminiferous tubular morphology was altered significantly, showing a reduction in height, perimeter and area in a dose dependent manner. Sertoli cell number decreased. Basement membrane thickness was reduced and it appeared to be permanent, with statistically insignificant changes even after 2 months. There was a reduction of intertubular spaces. Sperms have shown banana heading, decapitation and loss of normal hook of head. The effects were partially reversible at the end of 2 months.

CONCLUSION

It was concluded that gemcitabine affects the process of spermatogenesis adversely in a dose and time dependent manner and the effects are partially reversible.

Vanadium induced ultrastructural changes and apoptosis in male germ cells

Vanadium is a transition metal that is emitted to the atmosphere during combustion of fossil fuels. In the environment, vanadium occurs in the (V) oxidized form, but in the body it is found exclusively in the (IV) oxidized form. Vanadium tetraoxide is an inorganic chemical species in the (IV) oxidized form that has been shown to induce toxic effects in vitro and in vivo. The reproductive toxicity of vanadium in males was studied through monitoring germ cell apoptosis during spermatogenesis. We analyzed ultrastructural damage, and testosterone and progesterone concentrations following vanadium tetraoxide administered to male mice for 60 days. Spermatogenesis stages I-III and X-XII frequently showed apoptotic germ cells in control and treated animals; vanadium tetraoxide treatment induced an increase in the number of germ cell apoptosis in stages I-III and XII at 9.4 and 18.8 mg/kg, respectively. Although spermatogenesis is regulated by testosterone, in our study this hormone level was not modified by vanadium administration; thus, germ cell death was not related with testosterone concentration. At the ultrastructural level, we observed inclusion structures that varied as to location and content in the Sertoli and germ cells.

Gene expression analysis of the rat testis after treatment with di(2-ethylhexyl) phthalate using cDNA microarray and real-time RT-PCR

To investigate the effects of di(2-ethylhexyl) phthalate (DEHP) on gene expression in rat testis, 6-week-old male Sprague-Dawley rats were given a single oral dose of 20 or 2000 mg/kg and euthanized 3, 6, 24, or 72 h thereafter. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells were significantly increased in the testis at 24 and 72 h after the exposure to 2000 mg/kg of DEHP. On cDNA microarray analysis, in addition to apoptosis-related genes, genes associated with atrophy, APEX nuclease, MutS homologue (E. coli), testosterone-repressed-prostatic-message-2 (TRPM-2), connective tissue growth factor, collagen alpha 2 type V, and cell adhesion kinase were differentially expressed. To investigate the relationship between histopathological alteration and gene expression, we selected genes associated with apoptosis and analyzed their expression by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). With 20 mg/kg of DEHP treatment, bcl-2, key gene related to apoptosis, was increased. Up-regulation of bcl-2, inhibitor of Apaf-1/caspase-9/caspase-2 cascade of apoptosis, may be related to the fact that no morphological apoptotic change was induced after dosing of 20 mg/kg DEHP. With 2000 mg/kg of DEHP treatment, the apoptotic activator cascade, Fas/FasL, FADD/caspase-8/caspase-3 cascade, and Apaf-1/caspase-9/caspase-2 cascade were increased and bcl-2 was decreased. Thus, these gene regulations might lead the cells into apoptosis in the case of high exposure to DEHP. In contrast, FADD/caspase-10/caspase-6 cascade and caspase-11/caspase-3 cascade were not increased. These results indicate that the cascades of FADD/caspase-10/caspase-6 and caspase-11/caspase-3 are not related to apoptosis with DEHP treatment.

Long-term alteration of gene expression without morphological change in testis after neonatal exposure to genistein in mice: toxicogenomic analysis using cDNA microarray

In this study, we carried out toxicogenomic analysis using in-house cDNA microarray to ascertain the long-term effects of neonatal exposure to genistein, also known as phytoestrogen, on testicular gene expression in mice. Male ICR mice, 1 day after birth, were exposed for 5 days to genistein (1000 microg/mouse/day) or diethylstilbestrol (DES) (50 microg/mouse/day), used as an example of a potent estrogen, and their testes were used when they were 12 weeks old. Since exposure to DES was been reported to induce morphological changes and alteration of gene expression in reproductive organs, DES was used as a positive control. Genistein-treated mice did not show any histological abnormalities or increased apoptotic cells in testes, but these abnormalities and increases were found in DES-treated mice. On the other hand, mRNA expression analysis using in-house cDNA microarray revealed that 2 down-regulated genes (GeneBank accession No. W49392 and AI430907) were detected in genistein-treated mouse testes. Moreover, real-time PCR analysis revealed that mRNAs of the W49392 gene, estrogen receptor alpha (ERalpha) and androgen receptor (AR), were down-regulated in the testes of both genistein-treated and DES-treated mice. In our present study using toxicogenomic analysis, long-term alteration in testicular mRNA expression, without morphological change in testes, was detected after neonatal treatment with genistein, indicating that the W49392 gene, in addition to ERalpha and AR, might be useful as a biological marker for predicting the effects of neonatal exposure to DES and genistein.

Detection of mitomycin C-induced testicular toxicity by micronucleus assay in mice

Background, Aims and Methods:  Mitomycin C is a promising cancer agent that has been shown to inhibit DNA synthesis. Our previous study showed that mitomycin C induces spermatogenic cell apoptosis in the mouse testis. By using TdT-mediated dUTP-biotin nick-end labeling in the study, we confirmed that apoptotic cell death was most commonly found in the spermatogonia and less frequently found in spermatocytes in mitomycin C-treated mice. We therefore hypothesized that the spermatogenic cell apoptosis induced by mitomycin C occurred as the result of a mechanism to eliminate male germ cells with DNA damage or chromosomal aberrations. To test our hypothesis, we used a micronucleus assay for the detection of chromosomal damage induced in the spermatogonia or spermatocyte stages. Results and Conclusions:  The frequency of micronuclei was clearly increased in the mitomycin C-treated animals, and the number of micronuclei was greater at the spermatogonia or early spermatocyte stage than at the secondary spermatocyte stage. These results revealed that apoptosis and chromosomal aberration in the mouse testis after mitomycin C treatment occurred in the same cell types, that is, spermatogonia and spermatocytes. These findings indicate that chromosomal aberration of the spermatogenic cells induced by mitomycin C may have caused the spermatogenic cell apoptosis. (Reprod Med Biol 2003; 2: 69-73).

Methamphetamine induces apoptosis in seminiferous tubules in male mice testis

We investigated whether methamphetamine (MAMP) induces apoptosis in seminiferous tubules in 10-week-old male ICR mice. Methamphetamine was dissolved in saline and injected ip at four doses (1, 5, 10, and 15 mg/kg). TUNEL-positive cells were detected in the seminiferous tubules in animals 24 h after a single treatment with 5, 10, or 15 mg/kg MAMP. The percentage of seminiferous tubules containing more than three TUNEL-positive cells (apoptotic tubules) was considered a reliable indicator for apoptotic changes. After a single treatment with 10 mg/kg MAMP, the percentage of apoptotic tubules increased with time, and it became significant at 24 h, at which time vacuolar changes in spermatogonia also peaked. Although the percentage of apoptotic tubules increased dose dependently from 5 to 15 mg/kg MAMP, the DNA ladder was detected in the testis of 15 mg/kg MAMP-treated mice. Thus, we have demonstrated that MAMP induces apoptosis in seminiferous tubules in male mice testis.

Involvement of Bcl-2 family genes and Fas signaling system in primary and secondary male germ cell apoptosis induced by 2-bromopropane in rat

Epidemiological surveys and animal experimental studies suggest that exposure to 2-bromopropane (2-BP) could result in reproductive and hematopoietic disorders. The objectives of this study were to investigate the role of apoptosis in 2-BP-induced testicular toxicity and whether this process involves Bcl-2 family genes and the Fas signaling system. Rats were injected percutaneously with 1350 mg/kg 2-BP for 1 to 5 days and then were euthanized at 6 or 12 h after one dose, 6 h after two, three, or five doses, and 2 or 9 days after the final treatment. Light and electron microscopic analyses, TUNEL staining of DNA fragments, agarose gel electrophoresis of low-molecular-weight DNA, and Western blotting analysis of Bcl-2 family proteins and Fas receptor and ligand were conducted. Two-day treatment resulted in selective degeneration of spermatogonia with marked nuclear chromatin condensation. DNA ladder formation on the agarose gel further validated the findings of TUNEL-stained apoptotic cells. The percentage of apoptotic-positive tubules and apoptotic cell index increased time dependently. 2-BP treatment resulted in two distinct morphological changes: an immediate effect on spermatogonia and secondary apoptosis of spermatocytes 9 days after treatment. Downregulation of Bcl-2 after the first or second injection of 2-BP and upregulation of Bax after the first treatment contributed to the initiation of primary apoptosis of spermatogonia. Expression of FasL was inhibited while expression of Fas increased after the 2-BP treatment and remained at levels about two times of the control. However, it increased about sixfold of the control by day 9 after final injection, which contributed to the induction of secondary apoptosis of spermatocytes. Our results indicate that 2-BP resulted in apoptotic death of testicular germ cells and that this process involves the Bcl-2 family genes and the Fas signaling system.

Lead-induced cell death in testes of young rats

Lead is a well-documented testicular toxicant. The present work was planned to study the occurrence of germ cell death after lead administration. Young growing rats were treated with 5, 10 and 20 mg kg(-1) body weight of lead for 2 weeks. Cell death was assessed by employing in situ TUNEL staining, DNA electrophoresis and morphological examination of the tubules. The results showed that Pb induced significant numbers of germ cells to undergo apoptosis in the seminiferous tubules of rats treated with 20 mg kg(-1) body weight. However, DNA fragmentation was not detected at any of the doses. The level of lead accumulation in the testis increased in a dose-dependent manner.

Differences in sensitivity of murine spermatogonia and somatic cells in vivo to sister-chromatid exchange induction by nitrosoureas

Previously published data indicate that spermatogonia (SPG) are less sensitive to a sister-chromatid exchange (SCE) induction for different mutagens. In an earlier study, we have observed that bromodeoxyuridine (BrdU) substituted murine SPG are less sensitive to SCE induction by gamma ray in cells, than bone marrow (BM) and salivary gland (SG) cells in vivo. This was interpreted to mean that SPG are more efficient in DNA repair or are less prone to SCE induction. That the lower induction of SCE could be due to a reduced accessibility of mutagens to the SPG by virtue of a physiological barrier, was discarded by using gamma radiation. The aim of the present study was to establish whether or not there are differences in SCE induction by nitrosoureas among SPG, SG and BM cells with BrdU substituted or unsubstituted DNA. It was observed that SCE induction by methylnitrosourea (MNU) or by ethylnitrosourea (ENU) in SPG was, respectively, five and two times lower than in SG, and ten and three times lower than in BM. In SPG after BrdU incorporation, there was no increase in efficiency of SCE induction; in fact, there was even a slight decrease by exposure to MNU or ENU. BM and SG cells showed an increased efficiency in SCE induction after BrdU incorporation. This implies that SPG are also less sensitive to SCE induction by nitrosoureas, which cause a different kind of damage from previously assayed mutagens.

Nucleotide excision repair in rat male germ cells: low level of repair in intact cells contrasts with high dual incision activity in vitro

The acquisition of genotoxin-induced mutations in the mammalian germline is detrimental to the stable transfer of genomic information. In somatic cells, nucleotide excision repair (NER) is a major pathway to counteract the mutagenic effects of DNA damage. Two NER subpathways have been identified, global genome repair (GGR) and transcription-coupled repair (TCR). In contrast to somatic cells, little is known regarding the expression of these pathways in germ cells. To address this basic question, we have studied NER in rat spermatogenic cells in crude cell suspension, in enriched cell stages and within seminiferous tubules after exposure to UV or N-acetoxy-2-acetylaminofluorene. Surprisingly, repair in spermatogenic cells was inefficient in the genome overall and in transcriptionally active genes indicating non-functional GGR and TCR. In contrast, extracts from early/mid pachytene cells displayed dual incision activity in vitro as high as extracts from somatic cells, demonstrating that the proteins involved in incision are present and functional in premeiotic cells. However, incision activities of extracts from diplotene cells and round spermatids were low, indicating a stage-dependent expression of incision activity. We hypothesize that sequestering of NER proteins by mispaired regions in DNA involved in synapsis and recombination may underlie the lack of NER activity in premeiotic cells.

Involvement of germ cell apoptosis in the induction of testicular toxicity following hydroxyurea treatment

The present study investigated the occurrence of apoptotic cell death in the mouse testis at various intervals following the administration of hydroxyurea (HU). The presence of apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method and by DNA fragmentation assay using ligation-mediated polymerase chain reaction. Both the incidence of apoptotic cells and the level of DNA fragmentation in the testis increased depending on the HU dose, and they were most apparent at the highest dose (400 mg/kg). The incidence of apoptotic cells in the HU-treated group increased continuously and peaked at 12 h, but then decreased gradually, reaching control levels by 48 h. After HU treatment, TUNEL-positive apoptotic cells increased in the seminiferous epithelium of the tubules, and affected cells were found synchronously in the tubules of animals treated with HU. Spermatogonia and spermatocytes were found to be affected selectively. TUNEL-positive cells were found to be stage-specific and were primarily in stage IV-VI tubules. It has been shown that in vivo HU exposure induced testicular germ cell apoptosis dose dependently in a time- and stage-specific manner, and damaged cells appeared to be eliminated by phagocytosis by neighboring cells. Apoptosis of damaged testicular germ cells is apparently a common response to various testicular toxicants therefore protecting the next generations of germ cells from the damaged cell population.